Messages in this thread |  | | | Date | Tue, 03 Jan 2012 12:47:48 -0500 | | From | KOSAKI Motohiro <> | | Subject | Re: [PATCH v5 8/8] mm: add vmstat counters for tracking PCP drains |
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(1/2/12 5:24 AM), Gilad Ben-Yossef wrote: > This patch introduces two new vmstat counters: pcp_global_drain > that counts the number of times a per-cpu pages global drain was > requested and pcp_global_ipi_saved that counts the number of times > the number of CPUs with per-cpu pages in any zone were less then > 1/2 of the number of online CPUs. > > The patch purpose is to show the usefulness of only sending an IPI > asking to drain per-cpu pages to CPUs that actually have them > instead of a blind global IPI. It is probably not useful by itself. > > Signed-off-by: Gilad Ben-Yossef<gilad@benyossef.com> > CC: Christoph Lameter<cl@linux.com> > CC: Chris Metcalf<cmetcalf@tilera.com> > CC: Peter Zijlstra<a.p.zijlstra@chello.nl> > CC: Frederic Weisbecker<fweisbec@gmail.com> > CC: linux-mm@kvack.org > CC: Pekka Enberg<penberg@kernel.org> > CC: Matt Mackall<mpm@selenic.com> > CC: Sasha Levin<levinsasha928@gmail.com> > CC: Rik van Riel<riel@redhat.com> > CC: Andi Kleen<andi@firstfloor.org> > CC: Mel Gorman<mel@csn.ul.ie> > CC: Andrew Morton<akpm@linux-foundation.org> > CC: Alexander Viro<viro@zeniv.linux.org.uk> > CC: Avi Kivity<avi@redhat.com> > --- > include/linux/vm_event_item.h | 1 + > mm/page_alloc.c | 4 ++++ > mm/vmstat.c | 2 ++ > 3 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h > index 03b90cd..3657f6f 100644 > --- a/include/linux/vm_event_item.h > +++ b/include/linux/vm_event_item.h > @@ -58,6 +58,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, > THP_COLLAPSE_ALLOC_FAILED, > THP_SPLIT, > #endif > + PCP_GLOBAL_DRAIN, PCP_GLOBAL_IPI_SAVED, > NR_VM_EVENT_ITEMS > }; > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 092c331..4ca6bfa 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1140,6 +1140,10 @@ void drain_all_pages(void) > cpumask_clear_cpu(cpu, cpus_with_pcps); > } > on_each_cpu_mask(cpus_with_pcps, drain_local_pages, NULL, 1); > + > + count_vm_event(PCP_GLOBAL_DRAIN); > + if (cpumask_weight(cpus_with_pcps)< (cpumask_weight(cpu_online_mask) / 2)) > + count_vm_event(PCP_GLOBAL_IPI_SAVED);
NAK.
PCP_GLOBAL_IPI_SAVED is only useful at development phase. I can't imagine normal admins use it.
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